This section provides background information to facilitate a better understanding of the various aspects of the disclosure. It should be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art.
Devices for sealing and inflating inflatable objects are required in particular for puncture repair kits, which are arranged in the motor vehicle and carried by it in place of a spare tire.
In the case of such puncture repair kits for the temporary repair of tire punctures, in which the compressor units, i.e. the air compressors for filling a damaged tire, usually by way of a valve-and-distributor unit for sealant and compressed gas, are connected to the tire to be repaired, the valve-and-distributor unit also has a connector for the connection of a sealant container. For sealing the damaged tire, the sealant is then fed by the air compressor into the tire by way of the valve-and-distributor unit and after that the tire is inflated by the air compressor up to a certain minimum pressure.
The actual sealing of the damaged tire then takes place when the journey is resumed with the re-filled tire. The positive pressure on the tire and the outwardly acting centrifugal forces have the effect that the tire sealant is forced into the place where the tire is damaged (for example a puncture hole). The high shear forces and increased temperatures occurring here have the effect of initiating a chemical process in the tire sealant, which finally leads to a solidification of the sealant and a temporary sealing of the place that is damaged.
During the previously carried out process of feeding the sealant into the tire that is described above, the tire sealant is forced through the opened tire valve. The opening cross section present here corresponds approximately to the cross section of typical tire damage, and therefore certain measures are necessary to prevent the tire sealant from already solidifying and sealing in the tire valve. Apart from a chemical adaptation of the tire sealant, particularly the physical boundary conditions during the feeding of the sealant must also be chosen so as to prevent solidification of the tire sealant in the tire valve.
A high volumetric flow during the feeding of the sealant leads to high shear forces in the tire valve. In order to prevent resultant solidifying of the tire sealant, and therefore avoid clogging of the tire valve with sealant during the filling, the volumetric flow, and consequently the capacity of the air compressor used, may be limited. As a side effect, the air temperature at the compressor output is also reduced as a result. The consequently reduced heating up of the tire sealant likewise reduces its tendency to solidify. However, this approach has the disadvantage that less pumping power is available for the later inflation of the tire, against the leakage that is present, and consequently it is only possible to seal temporarily relatively minor damage to the tire.
An alternative to the described reduction of the volumetric flow is for example that of removing the tire valve during the filling with sealant. A complete removal of the tire valve during the pumping of the sealant dependably prevents a blockage of this constriction. This has the disadvantage, however, that the sealing process as such becomes much more complicated and laborious for the user.
A pressure-limiting solution of a more general nature is shown for example by DE 44 29 097 A1. Disclosed there is a compressor unit or a piston compressor with an outlet valve of a conventional type in the prior art, which at the same time is the only “pressure relief valve” for the interior space of the compressor. Such an outlet valve consists of a spring-loaded disk, which covers an outlet bore of the compression space in the cylinder and lifts off against the spring when there is corresponding pressure in the compression space. However, this does not address the risk referred to of the tire valve clogging with sealant during filling.